Surgical extractor

ABSTRACT

A surgical extractor for removing objects from a body including, for example, calculi, such as kidney stones and gall stones. The extractor includes a handle at an proximal end of the extractor with a slider for operation by a physician. At the distal end the extractor includes a plurality of wires with each wire comprising a first portion having an individual strand and a second portion comprising a plurality of filaments. When a retaining sheath is retracted, the wires, formed of a shape memory material such as stainless steel, expand such that each of strands assume a spaced relationship to define a first section of a basket and the plurality of the filaments assume a spaced relationship to define a second section of the basket. The use of a basket formed by wires having a first section comprising an individual strand and a second section comprising the plurality of filaments promotes capture of objects within the body by having widely spaced wires in the first section, retention of such objects in the second section by multiplying the number of contacts with entrapped object, and improved selective release of such objects without any deleterious effect on the reliability or size of the extractor. Additionally, use of the basket enables improved dislodgment and capture of embedded or impacted objects.

This is a continuation of U.S. patent application Ser. No. 09/636,213file Aug. 10, 2000, now U.S. Pat. No. 6,383,196 allowed, which is acontinuation of U.S. patent application Ser. No. 08/968,906, filed Nov.6, 1997 and issued as U.S. Pat. No. 6,168,603, which is a continuationof U.S. patent application Ser. No. 08/822,207, filed Mar. 20, 1997,abandoned, which is a continuation of U.S. patent application Ser. No.08/382,778, filed Feb. 2, 1995, abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally relates to medical instruments and morespecifically to an extractor for removing an object from a body,particularly calculi that can form in the biliary and urinary systems.

2. Description of Related Art

Recently developed medical instruments reduce the invasiveness andpotential trauma previously associated with various medical procedures.The removal of calculi in the form of kidney stones, gallstones and thelike from the body is one area where this effort is meeting withsuccess. Various instruments now permit the removal of kidney stones andgallstones without the need for major surgery. Some of these instrumentsincorporate miniaturized grasping forceps. This invention, however, isdirected to an alternative set of instruments that utilize mechanicalretrieval baskets.

The following United States Letters Patents and United States PatentApplication describe various types of such retrieval baskets:

U.S. Pat. No. 4,346,846 (1982) Dormia

U.S. Pat. No. 4,590,938 (1986) Segura et al.

U.S. Pat. No. 4,611,594 (1986) Grayhack et al.

U.S. Pat. No. 4,625,726 (1986) Duthoy

U.S. Pat. No. 4,807,626 (1989) McGirr

U.S. Pat. No. 5,064,428 (1991) Cope et al.

Ser. No. 08/258,121 (1994) Bates et al.

Dormia discloses a retrieval basket at a distal end of a surgicalextractor selectively extended beyond a tube in an enlarged condition.The retrieval basket comprises a plurality of wire pairs with the wiresin the pairs extending in opposite helical wound paths to providerelatively closer wire spacings in the distal end of the enlargedretrieval basket compared to the proximal end. The differential wirespacing promotes the capture of objects in the middle portion of theretrieval basket and entrapment of such objects in the distal end of theretrieval basket.

Segura et al. disclose a medical retrieval device that can be insertedthrough the working channel of an endoscope for removing stones and thelike from the kidneys or the ureter or biliary duct. A retrieval basketof relatively large diameter extends from the distal end of a sheath andcollapses into a compact form when drawn into the sheath. Individualoutwardly bowed spring strips form the retrieval basket. These stripsextend generally axially of the sheath and join at respective distal andproximal ends. The retrieval basket has a generally bulbous form whichis relatively stiff due to the spring strip construction and facilitatesdislodgment and capture of stones.

The Grayhack et al. patent discloses another retrieval basket that isuseful during the removal and/or destruction of calculi. A smooth outertubular sheath overlies and contains a stranded wire cable terminatingin a protective tip at the working or distal end of the device. When thecable is extended distally, the individual spring wire strands at theworking end of the cable expand to form a retrieval basket. The distalend of this device additionally includes an expandable distal portionfor protecting surrounding tissue during withdrawal of the device andcalculi.

The Duthoy patent discloses an extraction device that includes aretrieval basket formed from a plurality of individual wires spacedabout and outwardly from an imaginary extension of the center line of ahollow cable. A filiform extends distally from the distal end of theretrieval basket to extend past a stone and to allow the basket to bethreaded around and onto the calculi.

The McGirr patent discloses an extractor including a self-closingretrieval basket at the distal end of a catheter with a flexible controlline for opening the retrieval basket from the proximal end of thecatheter. The retrieval basket assumes a normal position wherein it isin a compact closed form. Pulling on the control line flexes individualstrips which define the retrieval basket to open the retrieval basket.When the control line is released, the strips relax and surround thecalculi or object being removed.

Cope et al. disclose a stone retrieval basket having superelasticindividual wire loops secured together at the apex of the loops todefine a distal end of a retrieval basket which can be insert throughand beyond a distal end of an elongated tube. Sleeves which secure thewires in a spaced relation and defines the proximal end of the retrievalbasket, so the retrieval basket has a bulbous shape.

Bates et al. disclose, in a co-pending patent application commonlyassigned with this application, a surgical retrieval basket comprisingaxially extending wires that are grouped in sets of filaments. The wiresare normally maintained in an overlying sheath in a compact conditionand form an enlarged retrieval basket upon retraction of the sheath. Theindividual filaments in a set are relatively closely angularly spacedwith the sets being relatively widely spaced to provide a greater numberof contact points with entrapped calculi without significantlyincreasing the manipulations necessary to capture such calculi in theretrieval basket.

These and other surgical extractors using retrieval baskets have certaincommon characteristics. Each retrieval basket comprises a plurality offilaments in the form of individual strands, strips or wires that extendfrom a proximal end of the retrieval basket to the distal end of theretrieval basket and, as disclosed by Cope et al., back to the proximalend. In some retrieval baskets the strands are formed alongsubstantially straight lines when the retrieval basket is in a compactform; in others, along a generally helical path. Each instrumentincludes a plurality of three or more such individual strands to providecontact points for entrapping objects and between which the objects mustpass for capture within the retrieval basket.

Retrieval baskets preferably include sufficient numbers of closelyspaced wires to provide an enclosure for retaining objects capturedwithin such retrieval baskets while having relatively few widely spacedwires for promotion of capture of such objects. Additionally, theoverall size or diameter of an extractor and ancillary equipment, suchas an endoscopic device, can impose upper limits on the number of wiresand the size of the individual wires. Thus, the design of such basketsinvolves a compromise between the numbers of wires needed to retainobjects and to promote capture of such objects and the overall size ofsuch wires for sufficient strength of the basket.

The following United States Letters Patents and United States PatentApplication describe retrieval baskets that include a material coatingover the distal end of the baskets to encapsulate objects to be removedfrom the body:

U.S. Pat. No. 3,472,230 (1969) Fogarty

U.S. Pat. No. 4,790,812 (1988) Hawkins, Jr. et al.

Fogarty discloses a surgical retrieval basket that extends from thedistal end of a catheter and comprises four spring wires that to aslide. An umbrella of suitable flexible material is connected to thedistal portion of the wires so that upon deployment of the retrievalbasket the edges of the umbrella form a circular scrapper. Retractingthe retrieval basket from a deployed condition toward and then into aproximal sheath removes debris from a body passage with the umbrellaretaining and then closing upon the captured debris.

Hawkins, Jr. et al. disclose a parachute retrieval basket deployed fromthe end of a catheter. The retrieval basket comprises four individualhelically wound spring wires that extend between proximal to distal endsof the basket. A thin, porous fabric web secures and covers the distalportion of the wires to thereby prevent passage of debris, such asemboli or atheroma therethrough.

These and other surgical extractors having a unitary material web at thedistal end have certain common characteristics. Each retrieval basketcomprises a plurality of filaments in the form of individual strands,strips or wires that extend from a proximal end to the distal end of theretrieval basket. Like the previously described retrieval baskets, thestrands lie either along substantially straight lines or extend along agenerally helical path when the retrieval basket is in a compact form.The retrieval baskets include at least four individual strands to whichthe web is attached along a distal portion.

The design of a web retrieval basket is also a compromise between (1)the numbers of the strands necessary to deploy the web in a sufficientlyopen, radially-extended edge, (2) the numbers of wires to promotepassage of objects through the wires into the retrieval basket, and (3)the overall size or diameter of an extractor and ancillary equipment,such as an endoscopic device with which the retrieval basket is used.These web baskets, however, are more difficult to manufacture than wireretrieval baskets, and further limit the diameter of the wires due tothe space occupied by the web in the compacted condition.

Thus, additional wires in either a wire or web retrieval basket would beadvantageous in certain respects and detrimental in others. For example,increasing the number of wires increases the number of contacts betweenthe basket and any entrapped calculi and, in the case of a web basketmore evenly opens the parachute. However, the resulting decrease in thespacing between such wires complicates the manipulations necessary foran expanded retrieval basket of either type to capture the calculi.Likewise, reducing the numbers of wires facilitates the capture of theobject between the wires and selective release of the object, if needed.However, the fewer contact points between the captured object and theretrieval basket make retention and entrapment of such objects moredifficult and, in the web basket, limit the radial extent of the web.

Additionally, most of these devices do not permit the retrieval basketto be dragged proximally along a surface to engage objects therealong.This would be particularly useful in the case of impacted calculi, e.g.,kidney stones, that now frequently require major surgery due to theinability of the prior art devices to remove them. Thus, while thedevices described above have some of the desirable features, noneprovide a device that is relatively simple to manufacture, promotes easeof capture of objects, promotes ease of percutaneous release of suchobjects, and promotes retention of relatively small objects captured.

SUMMARY

Therefore it is an object of this invention to provide a surgicalextractor that increases the reliability of retaining entrapped objectsin a retrieval basket.

Another object of this invention is to provide a surgical extractor thatincreases the number of contact points with entrapped objects in adistal portion of a retrieval basket without increasing the overall sizeof the instrument.

Still another object of this invention is to provide a surgicalextractor that promotes the selective release of entrapped objects.

Another object of this invention is to provide a surgical extractor thatenables the entrapment of objects embedded in bodily tissue.

Still another object of this invention is to provide a surgicalextractor that increases the number of contacts with entrapped calculiin an extractor that is readily manufactured.

Still yet another object of this invention is to provide a surgicalextractor that increases the number of contact points with entrappedcalculi and promotes ease of capture of such calculi.

Still a further object of this invention is to provide a surgicalextractor that provides an open wire web of a plurality of filaments ina distal portion and individual strands in a proximal portion tooptimize both the entry and capture of objects in the proximal portionof the retrieval basket and retention of such objects in the distalportion of the retrieval basket.

Yet a further object of this invention is to provide a surgicalextractor that provides relatively few individual wire strands topromote capture of objects.

Yet still a further object of this invention is to provide a surgicalextractor that decreases the number of interfering contact point wireswith an object at the proximal portion of the extractor while maximallyincreasing the number of contacts with the object at a distal portion toretain such object.

In accordance with this invention a surgical extractor for removing anobject from a body includes a retrieval basket with distal and proximalends and a retractable sheath. The retractable sheath in a firstposition retains the retrieval basket in a compact condition and in asecond position frees the retrieval basket for expansion to form anenlarged basket that comprises a plurality of wires extending betweenthe distal and proximal ends of the basket. Each of the wires of thebasket comprises a first section having an individual strand extendingfrom one end, such as the proximal end, of the basket and a secondsection having a plurality of individual filaments that extend betweenthe other end, such as the distal end, of the basket and the strand.

According to another aspect of this invention a surgical extractor forremoving an object from a body comprises a handle extending along anaxis that includes a base for being grasped by a physician and a sliderfor axial reciprocation relative to the base. The base connects withbasket forming means for forming a enlarged basket distally of thehandle. The basket includes a set of spaced, spring formed wires witheach of the wires have a first section comprising an individual strandand a second section comprising a plurality of spaced filaments ofwires. A sheath connects to the slider for axial displacement withrespect to the basket whereby the sheath in a first position retains thewires and in a second position exposes the first and second sections ofthe wires to enable the wires to expand and form the basket.

According to a further aspect of this invention a surgical extractor forremoving objects from a body comprises an axially extending, moldedplastic, partially hollowed base and a support. The support includes asolid stainless steel, radially flexible, axially stiff rod attached toand extending distally from the base, a stainless steel cable extendingdistally from the rod and a connector axially connecting the rod andcable. A plurality of spaced stainless steel wires attached to thedistal end of said cable. Each wire has a proximal portion comprising anindividual strand and a distal portion comprising a plurality offilaments. Proximal movement of a plastic slider captured in the basemoves a polyimide sheath and exposes the wires whereby the sheathcompacts and retains said wires at substantially a given diameter in itsdistal position and releases the wires from their compact form tothereby form an enlarged retrieval basket.

BRIEF DESCRIPTION OF THE DRAWINGS

The appended claims particularly point out and distinctly claim thesubject matter of this invention. The various objects, advantages andnovel features of this invention will be more fully apparent from areading of the following detailed description in conjunction with theaccompanying drawings in which like reference numerals refer to likeparts, and in which:

FIG. 1 is a plan view of a surgical extractor constructed in accordancewith this invention with a handle at a proximal end and an expandedretrieval basket at a distal end;

FIG. 2 is a enlarged view, partially in cross section, of the distal endof the extractor of FIG. 1;

FIG. 3 is a enlarged plan view of the distal end of the extractor ofFIG. 1 with the retrieval basket in a reduced, expanded form;

FIG. 4 is an enlarged view, partially in cross section, of the distalend of the extractor shown in FIG. 1 with the retrieval basket in acompact form;

FIG. 5 is an enlarged plan view of the distal end of another surgicalextractor incorporating another embodiment of a retrieval basket in anexpanded form;

FIG. 6 is an enlarged plan view similar to FIG. 5 of still anotherembodiment of a retrieval basket in an expanded form;

FIG. 7 is an enlarged plan view similar to FIG. 5 of yet anotherembodiment of a retrieval basket in an expanded form;

FIG. 8 is an enlarged plan view similar to FIG. 5 of yet still anotherembodiment of a retrieval basket in an expanded form;

FIG. 9 is an enlarged plan view similar to FIG. 5 of a furtherembodiment of a retrieval basket in an expanded form;

FIG. 10 is an enlarged plan view of the handle at the proximal end ofthe extractor shown in FIG. 1;

FIG. 11 is another view, partially in section, taken along lines 11—11in FIG. 10; and

FIG. 12 is a cross sectional view taken along lines 12—12 in FIG. 11.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIG. 1 depicts one embodiment of a surgical extractor 10 constructed inaccordance with this invention. The surgical extractor 10 includes ahandle 11 at a proximal end 12 having a base 13 and a slider 14. Aphysician can grasp the base 13 in the palm in his or her hand andmanipulate the slider 14 with his or her thumb. A retrieval basket 15formed in accordance with this invention is located at the distal end 16of the extractor 10. A sheath 17 overlies an intermediate supportingstructure between the handle 1 and the retrieval basket 15.

As shown in FIG. 1 the slider 14 is located at a proximal position 14A.As the slider 14 advances to a distal position 14B as depicted inphantom, the sheath 17 advances from the position depicted in FIG. 2through the position shown in FIG. 3 to the position illustrated in FIG.4. In FIG. 4 the sheath 17 compacts and covers the retrieval basket 15within a central aperture of the sheath. The sheath 17 typicallycomprises a polyimide tube or a tube of another material that exhibitsthe radial flexibility, axial stiffness, biocompatibility and hoopstrength of a polyimide tube.

FIG. 2 depicts the distal end 16 of the surgical extractor 10 in anenlarged form in which the retrieval basket 15 forms a basket assembly18 comprising three axially extending sections 19, 20, and 21. Thefirst, or most proximal, section 19 and the second, or intermediate,section 20 comprise individual prestressed strands 22. The third, ormost distal, section 21 comprises prestressed filaments 24 that extenddistally from each of the ends of the strands 22 to a cap 25.

Each of the strands 22 and the filaments 24 are formed of stainlesssteel or some other shape memory material. The cap 25 captures distalends of all the filaments 24 by soldering the filaments 24 in the cap25, by swaging or by some other method to define a distal end of thebasket 15. A sleeve 26 defines the boundary of the first and secondsections 19 and 20 and secures the strands 22 together thereat. Thestrands 22 lie in a parallel relationship between the sleeve 26 and asleeve 27 located at the proximal end of the basket assembly 18. Theindividual strands 22 are prestressed or preformed so that withoutrestraint they diverge from each other as they extend distally from thesleeve 26 through the intermediate section 20. The filaments 24 arepreformed to follow a helical path from the ends of the strands 22 toconverge at the cap 25 to thereby define the third or most distalsection 21 of the basket assembly 18.

While FIG. 4 illustrates the strands 22 extending essentially parallelto each other in the first and section 19, it will be understood thatthe strands 22 could be intertwined or twisted while still retaining acompact cross-section. Additionally, the strands 22 in the secondsection 20 could be preformed or stressed to follow a helical pathbetween the sleeve 26 and the third section 23. With either of theseconstructions, the distal end 16 of the extractor 10 remains radiallyflexible and, by virtue of the sheath 17, axially stiff to facilitateplacement of the extractor 10. The combination of radial flexibility andaxial stiffness is particularly important when the extractor 10 has theform shown in FIG. 4 with the sheath 17 advanced distally to the cap 25.

More specifically, a physician will introduce the extractor 10 with itsdistal end 16 in the form shown in FIG. 4 so the sheath 17 retains theretrieval basket 15 in its compact form. When the distal end 16 ispositioned proximate at calculi or any other object to be retrieved, thephysician moves the slider 14 from position 14B to the position 14A inFIG. 1. This retracts the sheath 17 and exposes the second and thirdsections 20 and 21 of the basket assembly 18. The wires return to theiroriginal shape as shown in FIG. 2 thereby to dilate surrounding tissueand to provide a structure that can be manipulated to capture calculiwithin the confines of the retrieval basket 15. Preferably, the distalend 16 of the extractor 10 is positioned distally of the object prior todisplacement of the sheath 17 so that the intermediate section 20 isadjacent or distally proximate the object to ease and speed capture ofthe object within the basket.

With the present invention, a physician can manipulate the retrievalbasket 15 so that the calculi or other objects between the filaments 24or strands 22 in much a similar manner as in prior art retrievalbaskets. However, the reduced number of strands 22 in the intermediatesection 20 greatly eases and simplifies this task.

Two different procedures for capturing calculi and the like demonstratethe ease with which the task can be realized. In a first, the physicianpositions the distal end 16 of the extractor 10 to or beyond thecalculi, moves the retrieval basket 15 out of the sheath 17 so theretrieval basket 15 expands beyond the calculi. As the physiciandisplaces the retrieval basket 15 proximally, the strands 22 canstraddle the calculi and allow the filaments 24 to capture the calculi.As an alternative, the distal end 16 can be positioned so the compactedretrieval basket 15 is coextensive with the calculi. Retracting thesheath 17 enables the retrieval basket 15 to expand around the calculiso subsequent withdrawal enables the strands 24 to capture the calculi.

The increased number of filaments 24 in the distal section 21 thatengage the calculi and urge it along as the extractor moves proximallyreduces the chances that the calculi can move between adjacentfilaments. The close spacing of the filaments 24 also allows forentrapment and retention of small objects which would not ordinarily beretained in retrieval baskets having the relatively wide spacing of thestrands 22 necessary to capture larger objects. Moreover, this featurecan be particularly useful in removing impacted or embedded calculi thatin the past generally required major surgery for removal, as theretraction of the basket 15 over such calculi tends to scoop it into thethird, web-like section 21.

Once the physician has moved calculi into the distal portion 10 of theretrieval basket 15, the physician advances the sheath 17 distally andreduces the volume of the retrieval basket 15 until it contacts theentrapped calculi (e.g., the volume of the basket shown in FIG. 3 withthe slider 14 in the position 14C shown in phantom in FIG. 1). Then thephysician withdraws the extractor 10 with the entrapped calculi from thepatient.

In some situations during withdrawal of the extractor 10, the retrievalbasket 15 and entrapped calculi must pass a stricture in a vessel. Insuch situations it may be desirable to terminate the procedure andwithdraw the extractor 10. With the extractor 10 according to thisinvention, the physician positions the distal end 16 distally of thestricture in a relatively open portion of the vessel. The physician thenmanipulates the retrieval basket 15 to urge the calculi to the proximalend of the expanded basket (i.e., the intermediate section 19) where thestrands 22 are widely spaced relative to the filaments 24 and thecalculi are most readily released from the retrieval basket 15. Then thephysician can advance the sheath to retain the retrieval basket 15 inits compact form thereby to facilitate the removal of the extractor 10from the body of the patient.

During manufacture of the specific embodiment of FIGS. 1 through 4,composite wires 28 are formed to extend axially with the strand 22constituting a first axial portion from which the second comprising thefour individual filaments 24 extends. The distal ends of all thefilaments 24 are soldered or swaged into the cap 25. The sleeve 26engages the strands 22 at the juncture of the first and second axialsections 19 and 20. It will be understood that the strands 22 cancomprise extensions of the four individual filaments 24 that are securedor otherwise entwined. Alternatively, the filaments 24 can constituteseparate filaments that attach to the distal end of each of the strands22 that comprise solid or braided wire. Applicants also note as afurther alternative that the sets of threads such as those disclosed bythe Bates et al. in U.S. patent application Ser. No. 08/258,121 andincorporated by reference herein can also be used with the presentinvention. Specifically, each of the strands 22 forming the proximalportion 18 of the retrieval basket 15 of FIG. 2, for example, wouldcomprise a plurality of closely spaced filaments and/or each of thefilaments 24 in the distal portion 19 of the basket 15 would comprise aplurality of closely space threads. In essence, this invention allowsthe construction of a retrieval basket in which the form and materialsof the first and second sections 20 and 21 can be tailored to meetcriteria including strength and flexibility.

After forming the composite wires 28 and attaching the cap 25 and thesleeve 26, prestressing the wires 28 occurs to form the retrieval basket15. The wires 28 intermediate the cap 25 and the sleeve 26 in theopposed ends of a forming tool. This tool extends transversely from acenter axis by a distance corresponding to the desired diameter of theretrieval basket 15. It rotates about its axis in the plane of the wiresback and forth approximately +75° and 75° so that each end of the toolslides along one of the wires and urge, and thus prestress, both of suchwires radially outward to define the basket 15 with the desireddiameter.

After the first tool is removed, two circular forming tools receive adistal and proximal portion, respectively, of each of the filaments 24with the filaments disposed essentially equiangularly about the tools.Rotation of the tools in opposite directions (i.e., counter-clockwiseand clockwise directions) prestresses the filaments 24 in the helicalfashion illustrated in FIGS. 1, 2 and 3. Consequently, the two strands22 are equiangularly spaced apart to facilitate the capture of largeobjects within the basket 15 while the relatively close angularlyspacing, approximately 45°, of the filaments improves retention ofsmaller objects in the web-like, distal portion of the basket 15. Itshould also be understood that the filaments 24 may be preformedsimilarly to that described above with respect to the strands 22 (i.e.,straight wire), and the strands 22 also may be preformed in the samemanner as the filaments 24 (i.e., helically wound).

Retrieval baskets according to this invention enable a user to select aretrieval basket which has both the advantages of baskets with arelatively few widely equiangularly spaced wires and those with closelyspaced wires, while avoiding the disadvantages associated with each.That is, the use of multiple filaments 24 in the third, or most distalsection 21 increases the number of contact points with any entrappedcalculi whereas the more widely spaced strands 24 in the intermediatesection 20 promote capture of such calculi. In FIG. 2, for example, theeight filaments 24 of the wires 28 provide multiple contacts for calculitherein rather than the contact which would be provided with a pair ofthe individual strands 22 extended through the third, or most distal,section 21. The close equiangular spacing of the filaments 24 alsopermits the retrieval basket 15 to accommodate surface unevenness ofsuch calculi to thereby increase its reliability and suitability. Thereduced number of strands 22 within the intermediate section 20 andincreased angular spacing between adjacent ones of the strands 22 allowa physician to maneuver the basket 15 to entrap and retain calculi moreeasily. This increased facility by means of increased numbers offilaments, such as quadrupling from two strands 22 to eight filaments24, occurs without increasing the overall size of the sheath 17 andwithout reducing the strength of the retrieval basket 15. For example,it is possible to place two individual strands having a diameter of0.010″ in a sheath 17 with an outside diameter of 3.0 Fr and to placeeight filaments having a diameter of 0.006″ in the same sheath due tothe change in packing efficiency.

When the sheath 17 moves from the position shown in FIG. 4 to theposition shown in FIG. 3, the expanded portion of the retrieval basket15 comprises only the distal section 21 of the basket 15. Thisconfiguration of the basket, while not providing the physician with thesame overall size and consequently narrow angular spacing of thefilaments through which the calculi must pass, can be used in locationswhere full expansion of the basket is impractical such as close to thewall of an organ or a narrow or otherwise weakened lumen in the body. Inany event, this feature allows further and diverse use of the retrievalbasket of this invention compared to prior retrieval baskets.

FIG. 5 depicts an alternative embodiment of a retrieval basket 15A andsheath 17A at a distal end 16A of the extractor 10A. In this particularembodiment, the retrieval basket 15A comprises four wires 48. Each ofthe wires 48 comprises a first section 48A and a second section 48B. Thefirst section 48A of each of the wires 48 comprises an individual strand22A extends through first and second sections 19A and 20A of a basketassembly 18A. The second section 48B of each of the wires comprises twofilaments 24A extending from the distal end of the associated one of theindividual strands 22A to a cap 25A to define a third distal section ofthe basket assembly 18A. The cap 25A captures the ends of all thefilaments 24A to define the distal end of the basket 15A, and a sleeveconnector 26A that secures the strands 22A together defines the proximalend of the basket 15A. In this particular embodiment each of the strands22A are angularly spaced by about 90° from adjacent strands, while thefilaments 24A are helical wound and angularly spaced by about 45°. Inthis particular embodiment, a filiform 49 extends distally from the cap25A. Such filiforms are know in the art and can be included as anelement in any embodiment of this invention.

FIG. 6 depicts only second and third sections 20B and 21B of the basketassembly 18B at the distal end 16B of another embodiment of a surgicalextractor 10B. Retraction of a sheath 17B at the distal end 16B of thesurgical extractor 10B to the illustrated position enables the secondand third sections 20B and 21B to form the enlarged retrieval basket 15Bextending between a cap 25B and a sleeve 26B. Two wires 58 define theretrieval basket 15B, with each of the wires comprising a individualstrand 22B extending distally from the proximal end of the end of thebasket and six filaments 24B extending proximally from the distal end ofthe basket to the distal end of the associated strand 22B. The filaments24B in this instance are prestressed to follow a helical path. Thestrands 22B of this embodiment comprise the associated filaments 24Bsecured together. Specifically, the filaments 24B are secured togetherby being entwined to define each of the strands 22B.

FIGS. 7, 8 and 9 illustrate other surgical extractor embodimentsconstructed in accordance with this invention. The retrieval baskets15C, 15D, and 15E of the extractors 10C, 10D and 10E comprise aplurality of wires with each of the wires having substantially morefilaments in the distal portion of the basket than strands in theproximal portion. For example, each of the two wires 68 of the basket15C of FIG. 7 comprises a strand 22C in the proximal section 21C andfive filaments 24C in the distal section, while each of the three wires78 of the basket 15D of FIG. 8 comprise a strand 22D and three filaments24D. Four wires 80 define the basket 15E of FIG. 9. Each includes anindividual strand 22E and four filaments 24E. Although, each of thefilaments 64, 74, and 84 of the baskets 15C, 15D, and 15E areprestressed, they are not helically wound like the filaments of thebaskets 15, 15A and 15B of FIGS. 1 through 6. That is each of thefilaments 24E between one of the strands 82 and the cap 25E isprestressed to extend radially away from the axis of the basket 15E andto be spaced from each of the other filaments. It will also be notedthat the extractor 10D of FIG. 8 also includes an expansible balloon 85connecting through a port 86 within an inflation source (not shown) forselective inflation of the balloon 85.

The baskets 15, 15A, 15B, 15C, 15D, and 15E described in connection withFIGS. 1 through 9 may also be formed by the method described in theco-pending, commonly assigned U.S. patent application Ser. No.08/342,911 filed on Nov. 21, 1994, “SURGICAL RETRIEVAL BASKET AND METHODFOR MAKING THE SAME”. Using the process described therein providesstrands and filaments with improved strength, durability and othercharacteristics.

As previously indicated with respect to FIG. 1, the sheath 17 extendsbetween the handle 11 and the distal end 16. An interconnecting linkallows the slider 14 to move the sheath 17 relative to the distal end16. This link comprises a radially flexible, axially stiff stainlesssteel cable 90 that is shown at its distal end in FIG. 4, and at itsproximal end in FIGS. 7 and 8. The sheath 17 retains the cable 90 on itsaxis.

Now referring to FIGS. 7 through 9, the proximal end of the cable 90attaches to a rod 91 by swaging, soldering or other method. The rod 91extends proximally into the handle 11. More specifically, the handlebase 13 includes a hollowed handle portion 92 with an internal boss orreceptacle 93 that receives the proximal end of the rod 91. Typicallythe proximal end of the rod 91 will be affixed in the receptacle 93 byan adhesive, ultrasonic or other fastening technique. Consequently, therod 69, the cable 90 and the basket 15 are fixed spatially with respectto the handle 11.

The slider 14 rides in an axially extending chamber 94 within the base13 formed with a radially extending slot 95. The slider 14 comprises acylindrical, elongated body 96 that has a radial passageway 97 forallowing the cylindrical body 96 to slide axially and freely in thechamber 94 with respect to the base 13 and the rod 91.

A thumb actuator 100 includes a thumb pad 101 and radial arm 102 thatare molded integrally with and extend radially from the cylindrical body96. The arm 102 extends through the slot 95 and is therefore slidablealong the axis of the extractor 10 between distal and proximalpositions. In this particular embodiment the base portion 11 includesradially extending bosses 103 and 104 that define the proximal anddistal terminations of the slot 95 respectively. The slider than movesbetween a proximal position, defined when the arm 102 reaches the boss103, and a distal position defined when the arm 102 reaches the boss104.

The distal end of the cylindrical body 96 supports a. Luer-lock fitting105. A first component or base 106 attaches to the cylindrical body 96and includes an axially extending aperture that allows the rod 91 topass through the fitting 105. A detachable component 107 carries thesheath 17. Consequently, as a physician moves the thumb actuator pad 101between proximal and distal positions, the slider 14 and the sheath 17move relative to the rod 91, the cable 90 and the retrieval basked 15(FIG. 1). Further as the thumb pad 101 moves toward the distal position,the distal end of the sheath 17, as shown in FIGS. 2 and 3, advancesover and compacts the strands 22 of the retrieval basket 15 due to theaxial stiffness and hoop strength of a polyimide tube or tube of similarmaterial.

Therefore, in each of the specifically disclosed embodiments anextractor that meets the various objects of this invention. Theextractor simplifies the capture and release of objects by providing arelatively few wires comprising individual strands at the proximal endof the basket. The extractor also provides for improved retention ofobjects captured thereby by providing a basket with a plurality of wireswith a plurality of filaments at the distal end. Specifically, in eachembodiment spaced, preformed wires each have individual strands in theproximal section and a plurality of spaced filaments at the distalportion. The spaced filaments increase the number of contact points withan entrapped calculi at the distal section of the basket. Yet there isno concomitant increase in the contact points in the number of wires orstrands in the proximal section of the basket.

This invention has been disclosed in terms of certain embodiments. Itwill be apparent that many modifications can be made to the disclosedapparatus without departing from the invention. For example, FIGS. 1 and2 depict a retrieval basket 15 with two prestressed strands 22 and eightfilaments 24. Each set of four filaments is interconnected only at theends thereof. Consequently the filaments 24 in each set may be widelyspaced where they join their respective strands 22. This opening, inappropriate circumstances, might be reduced by interconnecting adjacentstrands from each set by a connector, by joining or by some other means.Therefore, it is the intent of the appended claims to cover all suchvariations and modifications as come within the true spirit and scope ofthis invention.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:
 1. A method of manufacturing a surgical extractor,comprising: forming a plurality of wires, each wire comprising a strandand a plurality of filaments that extend from a distal end of thestrand, wherein the strand has a first axial portion and a second axialportion, the second axial portion located intermediate to the firstaxial portion and the plurality of filaments; preforming at least one ofthe plurality of wires by stressing the second axial portion of thestrand of the wire to diverge outward to define a basket having adesired diameter; and assembling the surgical extractor from theplurality of wires.
 2. The method of claim 1, wherein preformingcomprises preforming a pair of the plurality of wires by stressing thesecond axial portion of each strand of each wire of the pair of wires todiverge outward to define the basket having the desired diameter.
 3. Themethod of claim 1, further comprising capping together a distal end ofeach one of the plurality of filaments of each one of the plurality ofwires.
 4. The method of claim 1, further comprising attaching a sleeveto the plurality of wires, the sleeve defining a boundary between thefirst axial portion and the second axial portion of each strand.
 5. Themethod of claim 1, further comprising preforming the plurality offilaments of each of the plurality of wires in a helical fashion.
 6. Themethod of claim 5, wherein preforming the plurality of filamentscomprises rotating in opposite rotational directions distal and proximalportions of each of the plurality of filaments of each of the pluralityof wires.
 7. The method of claim 1, further comprising preforming thestrands in a helical fashion.
 8. The method of claim 1, wherein formingthe plurality of wires comprises forming the plurality of wires at leastin part from a shape memory material.
 9. The method of claim 8, whereinthe shape memory material comprises stainless steel.
 10. The method ofclaim 1, further comprising soldering the distal ends of the filaments.11. A method of removing an object from a body, comprising: providing anextractor comprising a retrieval basket with a distal end and a proximalend, a plurality of wires extending between the distal and proximal endsof the basket, each of the wires comprising an individual strandextending from the proximal end of the basket, a plurality of spacedfilaments extending between the strand and the distal end of the basket,and a sheath comprising a lumen for retaining the strands and filamentsof the retrieval basket in a first position in a compact conditionwithin the sheath lumen, and for freeing the retrieval basket in asecond position for expansion to form an enlarged basket for retrievingan object; positioning a distal end of the extractor adjacent to theobject; moving the retrieval basket out of the sheath; and capturing theobject by the plurality of filaments of the plurality of wires.
 12. Themethod of claim 11, wherein positioning comprises positioning theretrieval basket in a compact condition coextensive with the object, andmoving the retrieval basket comprises retracting the sheath to enablethe retrieval basket to expand around the object.
 13. The method ofclaim 11, wherein positioning comprises one of positioning the distalend of the extractor at and beyond the object, and moving the retrievalbasket comprises causing the retrieval basket to expand beyond theobject, and capturing comprises displacing the retrieval basketproximally to capture the object by the plurality of filaments of theplurality of wires.
 14. The method of claim 13, further comprisingmoving the sheath distally to reduce a volume of the retrieval basket.